The auto-generated code for the Blazor components produces an unfixable warning when using @implements or @inherits with a nullable generic type

[msynk]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

same as dotnet/aspnetcore#32733

When Nullable Reference Types are enabled (enable in the .csproj), referring to a supertype with nullable parts results in a generated .razor.g.cs which disables nullable reference types then uses one. This line:
@implements SomeGeneric<T?>
results in warning CS8669, "The annotation for nullable reference types should only be used in code within a '#nullable' annotations context. Auto-generated code requires an explicit '#nullable' directive in source.". However, there is no way to enable the nullable annotations context for the generated code or to disable it for the .razor file, leaving you in a catch-22 situation.

I can confirm this issue is back after the latest update of the dotnet SDKs (tested on 6.0.300 and also 6.0.400-preview.22301.10).

Expected Behavior

the auto-generated code for the Blazor components (generated by Microsoft.NET.Sdk.Razor.SourceGenerators.RazorSourceGenerator) should not raise the CS8669 warning.

Steps To Reproduce

Here is a repro to reproduce this issue: https://github.com/msynk/repro-blazor-nullable-generic-params

run dotnet build on a fresh code (without the auto-generated code in the obj folder) or run dotnet clean before the build command.

the warning is coming from this line:

@inherits BaseComponent<string?>

Exceptions (if any)

No response

.NET Version

6.0.400-preview.22301.10

Anything else?

> dotnet --info
.NET SDK (reflecting any global.json):
 Version:   6.0.400-preview.22301.10
 Commit:    25580ffe7a

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.19044
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\6.0.400-preview.22301.10\

Host (useful for support):
  Version: 6.0.6
  Commit:  7cca709db2

.NET SDKs installed:
  5.0.103 [C:\Program Files\dotnet\sdk]
  5.0.301 [C:\Program Files\dotnet\sdk]
  5.0.303 [C:\Program Files\dotnet\sdk]
  5.0.409 [C:\Program Files\dotnet\sdk]
  6.0.301 [C:\Program Files\dotnet\sdk]
  6.0.400-preview.22301.10 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.All 2.1.30 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.1.30 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.26 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.17 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 6.0.5 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 6.0.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 2.1.30 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.26 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.17 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 6.0.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 6.0.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 3.1.26 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 5.0.9 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 5.0.17 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 6.0.5 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 6.0.6 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

this is an image of the output of the dotnet build command:

[ysmoradi]

+1

[maryamhdr]

+1

[Bouke]

Shouldn't dotnet/roslyn@ddd7482 have fixed this issue by now? The fix landed in Visual Studio 17.0.